Article 1, Section 9, Clause 5
Joseph Story, Commentaries on the Constitution 2:§§ 1011--121833
§ 1011. The obvious object of these provisions is, to prevent any possibility of applying the power to lay taxes, or regulate commerce, injuriously to the interests of any one state, so as to favour or aid another. If congress were allowed to lay a duty on exports from any one state it might unreasonably injure, or even destroy, the staple productions, or common articles of that state. The inequality of such a tax would be extreme. In some of the states, the whole of their means result from agricultural exports. In others, a great portion is derived from other sources; from external fisheries; from freights; and from the profits of commerce in its largest extent. The burthen of such a tax would, of course, be very unequally distributed. The power is, therefore, wholly taken away to intermeddle with the subject of exports. On the other hand, preferences might be given to the ports of one state by regulations, either of commerce or revenue, which might confer on them local facilities or privileges in regard to commerce, or revenue. And such preferences might be equally fatal, if individually given under the milder form of requiring an entry, clearance, or payment of duties in the ports of any state, other than the ports of the state, to or from which the vessel was bound. The last clause, therefore, does not prohibit congress from requiring an entry or clearance, or payment of duties at the custom-house on importations in any port of a state, to or from which the vessel is bound; but cuts off the right to require such acts to be done in other states, to which the vessel is not bound. In other words, it cuts off the power to require, that circuity of voyage, which, under the British colonial system, was employed to interrupt the American commerce before the revolution. No American vessel could then trade with Europe, unless through a circuitous voyage to and from a British port.
§ 1012. The first part of the clause was reported in the first draft of the constitution. But it did not pass without opposition; and several attempts were made to amend it; as by inserting after the word "duty" the words, "for the purpose of revenue," and by inserting at the end of it, "unless by consent of two thirds of the legislature;" both of which propositions were negatived. It then passed by a vote of seven states against four. Subsequently, the remaining parts of the clause were proposed by a report of a committee, and they appear to have been adopted without objection. Upon the whole, the wisdom and sound policy of this restriction cannot admit of reasonable doubt; not so much that the powers of the general government were likely to be abused, as that the constitutional prohibition would allay jealousies, and confirm confidence. The prohibition extends not only to exports, but to the exporter. Congress can no more rightfully tax the one, than the other.
Story, Joseph. Commentaries on the Constitution of the United States. 3 vols. Boston, 1833.
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